World's most powerful diesel engine

Hi,

For those who are interested. I believe it's an SDI. :

- 108,920 horsepower at 102 RPM.
- 25.480 liters of displacement.




Sure, here's the translation:

'Bor ey' translates to 'Hey, dude' or 'Hey, man' in English.
arnehttp://www.bath.ac.uk/~ccsshb/12cyl/{MARKER}

turbocharged two-stroke

Does that mean it's a turbocharged 2-stroke engine?

Two-stroke diesel engines always have a scavenging blower. This is often achieved using a Roots blower, as otherwise the large volume of air that needs to be moved from one end of the engine to the other would be impossible to manage. Therefore, it is neither a TDI nor an SDI. It's a turbocharged direct injection engine!

Sure, those kinds of things are amazing. I'd really like to experience them in person .

That's correct about the blower, but then it's just a regular two-stroke engine.
Large engines like these are always turbocharged. This is possible with two-stroke engines as well, starting at a certain size, using turbochargers. Otherwise, they use mechanical superchargers.
Without recharging, the efficiency drops too much.
These are the turbochargers that RWE uses as turbines in the power plant .

By the way, the PF pumps were designed for engines like these, which I mentioned in the quiz. As a standard part, they can deliver up to 1.8 liters of fuel injection per stroke. It's mind-boggling.

CU Gremlin.

Yesterday, N24 showed how a ship diesel engine block (120 tons) is cast at MAN Augsburg. It's quite impressive, even though the part is nowhere near as large as the engine linked above.

120 tons of iron are cast into the mold in 100 seconds. It then cools for 17 days(!) and is still approximately 300°C hot when it comes out of the mold.
The mold is weighted down with 900 kg at the top to prevent the material from floating.

It's already quite fun...

CU Gremlin.

I've also been doing some thinking about it...

... and I've come to the conclusion that you can't "charge" a two-stroke engine. The intake and exhaust ports are open at the same time. The scavenging blower only blows fresh air into the intake ports, which are only fully open at the top dead center (TDC) of the piston's stroke. As a result, the exhaust gases escape through the exhaust valve in the cylinder head. There is no pressure build-up (supercharging). That's probably why it's referred to as a "scavenging blower" and not a "turbocharger," even though it's structurally similar. This type of flushing is necessary because, unlike a moped engine, a ship's diesel engine does not have pre-compression in the crankcase.

Furthermore, I've been wondering (for quite some time) about the purpose of the connecting rod, as it increases the overall height of the engine. I've now come to the conclusion that it prevents tilting moments, which normally arise from the bearing of the piston in the upper connecting rod eye. I have a picture in mind of a piston from a single-cylinder motorcycle engine (long-term test) with the comment: "Wear marks due to piston tilting, a common problem in large single-cylinder engines." Of course, we're not talking about single-cylinder engines here. But the pistons are already quite large.

Not everything I've written has to be correct; I'm not an expert. So, feel free to criticize me.

mcgregg

Hi,

In 2-stroke engines, the exhaust port typically opens first, followed by the transfer ports (or overflow channels) and then the intake port. That is to say, there is a time interval during which exhaust gases can already escape before the openings for fresh air/fresh gas open.
Otherwise, it simply wouldn't work properly.
Therefore, it should also work with a turbocharger if the valve timing is made asymmetrical.

Best regards, Rainer.

You're right about the crosshead. It's really about the lateral forces that wouldn't be manageable with a conventional crankshaft. The wear on the pistons and cylinder liners would be enormous.
regarding this topic, it is worth noting that every motor is essentially made up of individual single-cylinder units .

What always amazes me are the SSPs (Service Publications). There, things like 'piston bolt axis alignment' are always presented as absolutely innovative novelties (most recently with the 2.0 TDI). Engine manufacturers have been dealing with such things for over 80 years .


However, you've fixed the issue with the charging.

All large diesel two-stroke engines use direct scavenging. Now, intake can be achieved either through ports or through valves in the cylinder head. And then you can achieve excellent supercharging. There are also pure port-controlled two-stroke engines with supercharging (using reverse or cross scavenging). For this, a supercharging slide is needed in the exhaust port, which essentially acts like a valve, allowing for supercharging. This method has also been used in large diesel engines.

Technically, there's nothing different between this and a 4-stroke engine. In both cases, the exhaust valve must be closed before the turbocharger can properly force air into the cylinder. In both methods, the actual charging process must be complete before the compression stroke begins.

Take a look at the websites of MAN or MTU.

Sure, here is the translation of the text from German to English:

'Cu Gremlin'

Hi Gremlin (and the others).

I would even go a step further in my phrasing and claim:

A two-stroke engine simply won't run without scavenging, as it's unable to draw in air on its own.

For small engines, the crankshaft case is often used as a simple solution, but this is a makeshift approach because it can never achieve a charging factor greater than 1. The type of rinse is completely irrelevant in this case.

Everything else uses blowers (or compressors - it's essentially the same thing).
There were also once two-stroke engine models with radial engines that had a scavenging blower, and they reportedly ran quite well. Definitely with more power and fewer lubrication problems than the current 4-stroke radial engines.

Unlike a 4-stroke turbo-diesel engine, whose efficiency increases (slightly) with turbocharging, the efficiency of a 2-stroke diesel engine drops rapidly because the residual energy in the exhaust gases is no longer utilized. A TDI engine with a turbocharger that produces boost pressure greater than atmospheric pressure generates torque on the crankshaft even during the intake stroke.

Yes, but why are ship diesel engines built as two-stroke engines? Then, they should also have a better efficiency as four-stroke engines.

Regards,
Jan.

Hello,

because they would then need to have twice as much displacement or cylinders. In this case, we have 50 m³ instead of "only" 25 m³. In a 4-stroke engine, there is only one ignition for every two revolutions, while in a 2-stroke engine, there is one ignition for every revolution.

Sincerely,
Christian

Exactly!

In direct injection engines, the scavenging losses are eliminated, which suddenly gives the 2-stroke engine a significant power advantage over the 4-stroke engine (simply put).

In the post-war period, there were attempts with direct injection and two-stroke engines. Even then, the advantages were significant. However, the injection technology was not yet fully developed.

Sure, here is the translation of the text from German to English:

'Cu Gremlin'

@ Gremlin,

'Meanwhile, it works, and there are even a few German patents related to it, and there were experimental and pre-production engines. (For example, orbital engines.)'

However, since modern car engines are designed to act as air purifiers, meaning the exhaust should be cleaner than the air intake, this engine principle (2-stroke direct injection) was ultimately discontinued. And that's despite being small, lightweight, fuel-efficient, and inexpensive, etc.

In the USA, there were (and possibly still are) 12-cylinder, 2-stroke diesel truck engines.

However, since modern car engines are supposed to function as air purifiers, meaning that what comes out the exhaust should be cleaner than what is sucked in, this engine principle (2T-DI) was ultimately discontinued. And that's despite being small, lightweight, fuel-efficient, and inexpensive, etc.


I don't quite understand this explanation. The direct injection in the cylinder actually mitigates the typical two-stroke engine problem, which is that unburned fuel can enter the exhaust port during the scavenging process (leading to environmental pollution). Aside from soot, in a two-stroke diesel engine, no unburned fresh fuel can enter the exhaust port because fresh fuel is not present during the scavenging process (unlike in a two-stroke gasoline engine).

On the contrary: Since a flush is never 100% complete (there are always residual exhaust gases in the cylinder), it actually creates an internal EGR (Exhaust Gas Recirculation) effect.

So, as I said, two-stroke Otto engines with external mixture formation definitely stink. But can't two-stroke diesel engines, in principle, be just as verschandeln as four-stroke engines?

There must be another reason why the two-stroke diesel engine has only become established in large engines.

It might be more expensive to manufacture overall due to the complex blow-out valve and the outlet valve. Perhaps the issue is simply that the rinsing process isn't thorough enough at high speeds, because the gas exchange in a 2-stroke engine occurs four times faster than in a 4-stroke engine.
Four-stroke engine: Power stroke + intake stroke = one kilowatt revolution.
Two-stroke engines: complete gas exchange around the upper dead center (UT), estimated to occur within approximately 1/4 of a crankshaft revolution.

Perhaps it's a combination of both problems: Because large engines are expected to achieve an extremely high operating lifespan due to their price, they are often operated at lower speeds than theoretically possible. At these lower speeds (relative to the engine size or stroke), a thorough two-stroke scavenging process is achieved so effectively that the two-stroke principle can be applied.

And another thing: Perhaps the highly optimized 2-stroke diesel engine has a narrower usable RPM range because the aerodynamic flow processes during the scavenging cycle are optimized for very specific engine speeds.

As far as my hypotheses go, and unfortunately they are only hypotheses, I would be truly interested in knowing the real reasons.

Best regards,

Hello there,

"Based on my own experience with ship diesel engines (although not ones with a 25 cubic meter capacity), I can say that such an engine on the bridge isn't controlled by an accelerator pedal. It's installed in the ship, started up, and then runs at its constant speed of 102 RPM for its entire life. The driver of a car with a 6-speed gearbox would be incredibly envious of that. And on more modern ships, the shaft and propeller rotate at a constant speed, and only the propeller blades are adjusted to vary direction and speed. Two-stroke diesel engines are the standard in large engine construction. Just imagine the valves that would be needed to allow air into the engine." "This quickly leads to a problem with the overall height, as these engines are anything but lightweight, and a low center of gravity is incredibly important for the ship. Also, the Roots blowers don't operate at nearly the same pressure as the ones on our TDI engines (referring to mini diesel engines)." The scavenging system, as correctly stated here, has the task of forcing air into the cylinder, since the engine itself either doesn't draw air in or only does so weakly.
Four-stroke diesel engines on ships are typically either high-speed or medium-speed engines. High-speed engines usually operate around 980 RPM. For example, all MTU V32 engines, which all feature a sophisticated common rail system, are four-stroke engines. These engines are used in luxury yachts, by the German armed forces, and on smaller to medium-sized ships. Such a "diesel monster" (although it's really just the diesel principle at work, as the fuel is the problematic heavy oil) only powers huge container ships or tankers.

@seatarosa

Hi,

Let's just talk about diesel for a moment. You're right about the unburned fuel, but:

Firstly, two-stroke engines are very sensitive to exhaust back pressure, so catalytic converters and particulate filters are problematic.
'2. Two-stroke engines always tend to draw some oil through the exhaust ports, so oil consumption is generally higher in two-stroke engines, even with separate lubrication (which, in this case, means an oiling system similar to that of a four-stroke engine), and they produce oil mist in the exhaust.'
The power output as a function of speed is likely to be relatively constant during operation with a wash pump, while with pre-compression...
The crankcase is known to be a relatively confined space where power is generated, as it creates a resonance system.

Exhaust valve/flap - is not strictly necessary, only required with high boost pressure, which goes against efficiency.
An intake valve is generally more useful for ensuring a consistent power output.

I'm not sure exactly where the problems arose during the testing process, but the fact is that you failed to meet the legal requirements, both here and abroad.
I could imagine them being used as auxiliary engines for hybrid drives, but even then, they would fail to meet Euro 5 standards. (In this particular case, a small, cheap, and lightweight engine with a fixed/optimal speed would be needed.)
The earlier NSU formula 3=6 was intended to express that a 3-cylinder 2-stroke engine, with its vibration level, would operate similarly to a 6-cylinder 4-stroke engine, and that a 2-cylinder 2-stroke engine would operate similarly to a 4-cylinder 4-stroke engine.

But for that, no one is developing a completely new generation of engines.
I drove a Toyota Prius hybrid a few days ago. It's interesting, but in terms of the necessary shift towards hybrid technology, it only represents the first 10 centimeters of the journey.


The large engines are not run at higher speeds, among other things, because the efficiency of the ship's propellers would decrease rapidly. Otherwise, a gearbox would be necessary. This is expensive, heavy, and also quite prone to failure at these power levels. It's not just about the torque that needs to be transmitted; the engine represents a large rotating mass, the shaft has a certain elasticity, and the propeller is again a rotating mass. The gearbox in between must also be able to handle the torsional vibrations that occur.
This two-mass problem is quite interesting and challenging in terms of calculation and implementation.
And if the transmission is running with a 98% efficiency, which would be really good, then it would generate a significant amount of waste heat at 30-100 tons of horsepower.
Therefore, transmissions are typically only used in 'high-performance' applications, as described by Mathias, within the range of up to several thousand horsepower.